Safety mechanism for presses, machines and fixtures

ABSTRACT

A safety mechanism including a hand restraint safety mechanism for use by an operator of a machine such as a press, special machine or fixture wherein (absent the present invention) the operator&#39;&#39;s hands are exposed to the hazard of being caught in the work area of the machine by moving machine elements when the machine is stroked. The hand restraints for the operator&#39;&#39;s hands are operatively coupled via cables with a fluidic power cylinder mounted in fixed dimensional relation to the machine with which the safety mechanism is used. This restraint cylinder is operative between restraining and released positions to control the length of each cable extended from a housing on which the cylinder is mounted. When the cables are maximally extended, the operator can reach into the machine to load or unload a workpiece. When the cables are minimally extended, the operator&#39;&#39;s hands are positively removed from the work area of the machine. A safety block mounted on the machine is operatively coupled with a second power cylinder for movement into and out of the work area of the machine. When the safety block is displaced into the machine work area, it mechanically prevents the machine elements from closing should the machine be accidentally stroked. A pneumatic control circuit is operatively coupled with the machine and includes multiple failsafe valves arranged to sense the operating positions of the cylinders and the machine for controlling the operation of the cylinders in a desired fashion. A cycle start signal to the machine is provided only when both the hand restraints and the safety block are retracted from the work area, and the safety block can be retracted only after the hand restraints have been retracted. The operator&#39;&#39;s hands are thereby maintained safe in a restrained position until the safety block is again extended into the work area after the machine has been stroked. After movement of all elements on the machine has terminated, the hand restraints are released to permit the operator manual access to the machine work area.

- United States Patent [191 Williamson 1 May 20, 1975 SAFETY MECHANISMFOR PRESSES,

MACHINES AND FIXTURES [76] Inventor: Robert W. Williamson, 77 CedarAcres, Brunswick, Ga. 37520 22 Filed: Jan. 23, 1974 21 Appl. No.:435,900

Related U.S. Application Data [63] Continuation-in-part of Ser, No.351,516, April I6,

1973, Pat. No. 3,847,259.

Primary ExaminerAllan D. Herrmann Attorney, Agent, or Firm-Harness,Dickey & Pierce 57 2 ABSTRACT A safety mechanism including a handrestraint safety mechanism for use by an operator of a machine such as apress, special machine or fixture wherein (absent the present invention)the operators hands are exposed to the hazard of being caught in thework area of the machine by moving machine elements when the machine isstroked. The hand restraints for the operators hands are operativelycoupled via cables with a fluidic power cylinder mounted in fixeddimensional relation to the machine with which the safety mechanism isused. This restraint cylinder is operative between restraining andreleased positions to control the length of each cable extended from ahousing on which the cylinder is mounted. When the cables are maximallyextended, the operator can reach into the machine 'to load or unload aworkpiece. When the cables are minimally extended, the operator's handsare positively removed from the work area of the machine. A safety blockmounted on the machine is operatively coupled with a second powercylinder for movement into and out of the work area of the machine. Whenthe safety block is displaced into the machine work area, itmechanically prevents the machine elements from closing should themachine be accidentally stroked. A pneumatic control circuit isoperatively coupled with the'machine and includes multiple failsafevalves arranged to sense the operating positions of the cylinders andthe machine for controlling the operation of the cylinders in a desiredfashion. A

' cycle start signal to the machine is provided only when both the handrestraints and the safety block are retracted from the work area, andthe safety block can be retracted only after the hand restraints havebeen retracted. The operators hands are thereby maintained safe in arestrained position until the safety block is again extended into thework area after the machine has been stroked. After movement of allelements on the machine has terminated, the hand restraints are releasedto permit the operator manual access to the machine work area.

53 Claims, 21 Drawing Figures PMENTED MAY 2 0 I975 SHEET an; 6

/i//4 4 4445 5 wal f SAFETY MECHANISM FOR PRESSES, MACHINES AND FIXTURESCROSS REFERENCE TO RELATED APPLICATION This application is acontinuation in part of my copending application entitled SafetyMechanism For Special Machines and Fixtures, Ser. No. 351,516, filedApr. 16, 1973, now issued as US. Pat. No. 3,847,259 on Nov. 12, 1974.

BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates toa safety mechanism including hand restraint safety mechanism for use byan operator of a machine having moving machine elements.

l-Ieretofore, various types of hand restraining apparatus of the type towhich the present invention relates have been used to remove the machineoperators hands from the path of travel of moving machine elements. Inone type of prior hand restraint apparatus, the operators hands areremoved from the danger area as the machine operates. Thus, theoperators hands can still be in the danger area as the machine elementsbegin to move. A hand restraining safety apparatus which eliminates theabove situation by preventing the machine from cycling until theoperators hands are in a safety position remote from the machine isdisclosed in copending application of the same inventor for SafetyMechanism for Special Machines and Fixtures, Ser. No. 351,516, filedApr. 16, 1973, now Pat. No. 3,847,259. In certain respects the presentinvention represents an improvement upon the safety apparatus of thateariler filed application.

Accordingly, one important objective of the present invention is toprovide a safety mechanism for use by a machine operator wherein notonly is movement of elements on the machine prevented until the.operators hands are disposed in a safety position remote from themachine, but also a mechanical safety interlock remains interposedbetween relatively movable machine elements until the operators handsare in the safety position. Only after the safety mechanism displacesthe operators hands to the safety position is the mechanical interlockremoved and then only with both the mechanical interlock removed and theoperators hands in the safetyposition is the machine stroked. At the conclusion of the machine stroke the mechanical interlock is reestablishedbefore the hand restraint are released. Hence, a further object of theinvention is to provide increased operator safety for the operators ofvarious types of machines such as presses, special machines andfixtures.

The particular details of the present invention by which the foregoingobjects are attained include a novel pneumatic control circuit havingfailsafe valve means operatively associated therewith to sense operatingpositions of various moving elements of the safety mechanism and themachine with which it is in use. Each failsafe valve means can pass afluidic signal only when the element whose position is to be sensed isthe intended position. By virtue of the unique arrangement of thesefailsafe valve means in pneumatic circuit, proper sequential operationof the various elements is always assured thereby providing maximumoperator safety. In the preferred embodiment of the invention disclosedherein, the particular details of the novel pneumatic control circuitconstitute further inventive features of the present disclosure.

One especially important improvement of the present invention involves anovel non-repeat circuit for the safety mechanism which prevents thesafety mechanism from being repeatedly operated and the machine frombeing repeatedly stroked so long as the actuating element for initiatinga machine cycle is held in the actuating position. Because of thisbeneficial feature, accidental cycling, and hence loss of productiontime, is eliminated.

The foregoing objects and features of the invention along withadditional features, advantages and benefits of the invention will beseen in the ensuing description and claims which are to be taken inconjunction with the accompanying drawings. The drawings illustrate apreferred embodiment of the invention in accordance with the best modepresently contemplated for carrying out the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of apreferred form of safety mechanism according to the present inventionmounted on and operatively coupled with arproduction machine andillustrating the usage of the present invention by the machine operator.

FIG. 2 is a view taken along line 2?-2 in FIG. 1.

FIG. 3 is an enlarged view of FIG. 2 and having a portion removed. 1

FIG. 4 is an enlarged view taken along line 4--4 in FIG. 3.

FIG. 5 is an enlarged view taken along line 5-5 in FIG. 3. e e

FIG. 6 is an enlarged sectional view taken along line 66 in FIG. 3. I e

FIG. 7 is an enlarged sectional view taken along line 7-7 in FIG. 3.

FIG. 8 is a left side elevational view of FIG. 7

FIG. 9 is a right side elevational view of FIG. 7.

FIG. 10 is an enlarged sectional view taken along line.

1010 in FIG. 7.

FIG. 11 is a schematic diagramof a portion of the pneumatic controlcircuit of the safety mechanism of FIG. 1. 1

FIG. 12 is a scheinaticdiagram of the remainder of the pneumatic controlcircuit of the safety mechanism of FIG. 1 and is to be taken inconjunction with FIG. 11.

FIG. 13 is a side elevational view of one of the failsafe valves whichis used in the pneumaticcontrol circuit of FIGS. 11 and 12.

' FIG. 14 is a sectional view taken along line 14-14 in FIG. 13. I

FIG. 15 is a longitudinal half sectional view of another form of valve.7 e i 1 FIG. 16 is a transverse sectional view taken along line 1616 inFIG. 15.

FIG. 17 is a longitudinal lhalf sectional view of another form of valve.

FIG. 18 is a transverse sectional view taken along line 18-18 in FIG.17.

FIG. 19 is a longitudinal half sectional view of a valve actuator.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1 and 2 illustrate asafety mechanism 100 according to the present invention in use with aproduction machine 102 having a vertically reciprocally strokeablemachine element 102a. Safety mechanism 100 comprises in part a handrestraint safety mechanism 100a contained in a housing 100a mounted infixed dimensional relation to machine 102 by means of a mountingstructure 104. Sufficient space is provided between housing 100a andmachine 102 to accommodate a machine operator 106. The operators hands108 and 110 are respectively engaged with a pair of conventional handrestraints 112 and 114 respectively which are attached to the ends offlexible restraining cables 116 and 118 respectively extending fromhousing 100a. The solid line positions of hands 108 and 110 and handrestraints 112 and 114 illustrate hand restraint safety mechanism 100ain the released position. In this position, sufficient lengths of cables116 and 118 extend from housing 100a to permit operator 106 to move hishands 108 and 110 into the machine work area for loading and/orunloading a workpiece. Absent the present invention, the operators handsare exposed to the hazard of being caught by machine element 102a duringits stroke. In view of the relatively fast operating speeds of certaintypes of machines, this can be an extremely hazardous situation. Thebroken line position of hand restraints 112 and 114 illustrates handrestraint safety mechanism 1000 in the restraining position. In thisposition, sufficient lengths of cables 116 and 118 are drawn intohousing 100a to prevent operator 106 from moving his hands 108 and 110into the machine work area.

Safety mechanism 100 further includes a mechanical interlock in the formof a safety block 119 mounted on machine 102 and arranged for movementinto and out of the path of travel of machine element 102a. Safety block119 is operatively coupled with the rod 63a of a power cylinder 63 toeffect displacement thereof into and out of the machine work area. Thesize and strength of block 119 are such that when disposed in the pathof travel of element 102a (i.e., in the extended or safety position asillustrated by the solid line position in FIG. 1), it will interrupt andlimit the downward stroke of element 102a to prevent closure of element102a on a workpiece should element 102a be stroked for any reason.Further, safety mechanism 100 is arranged such that when block 119 is inthe safety position and hand restraint safety mechanism 100a is in thereleased position, the operators hands 108 and 110 cannot be displacedfar enough to be caught between block 119 and element 102a. Also, thevertical dimension of block 119 is such that adequate hand clearance isprovided between element 102a and the workpiece when element 102a isclosed on block 119. Thus, block 119 provides a mechanical safetyinterlock with machine 102 whereby full closure of machine element 102acan be prevented with block 119 in the safety position. As will be seenin greater detail hereinafter, machine 102 cannot cycle until both theoperators hands 108 and 110, as well as safety block 119, are removedfrom the path of travel of machine element 102a and one of the inventivefeatures of the present disclosure involves the way in which theoperation of various elements of safety mechanism are interlocked witheach other and with machine 102.

In order to facilitate the readers understanding of the ensuing detaileddescription, it is desirable to summarily describe the operation of thesafety mechanism 100 in relation to the operation of machine 102. Withmachine element 102a stopped at its uppermost limit of travel, safetymechanism 100 first operates safety block 119 to the safety position andthen hand restraint safety mechanism 100a to the released position.Since cables 116 and 118 are now maximally extended from housing 100a,operator 106 can reach his hands into the work area to load a workpieceinto the machine. It will be observed that should element 102a beaccidentally stroked with the hand restraint safety mechanism 100a inthe released position, that safety block 119 will prevent element 102afrom closing on the operators hands should they be in the work area ofthe machine. After the workpiece has been loaded, operator 106 actuatesa starting device which may be in the form of a foot pedal valve 60(FIG. 1). Safety mechanism 100, in response to the actuation of valve60, first operates hand restraint safety mechanism 100a to therestraining position thereby drawing cables 116 and 118 into housing100a and positively removing the operators hands from the machine workarea. Only when mechanism 100a is in the restraining position is block119 removed to its retracted position out of the path of travel ofmachine element 102a. Now only with both hand restraint safety mechanism100a in the restraining position and safety block 119 in the retractedposition can the machine operating cycle be initiated. During the strokeof machine element 102a, safety mechanism 100 prevents cables 116 and118 from being extended from housing 100a and prevents safety block 119from being shifted to the safety position. Thus, while machine element102a is moving, the operators hands and safety block 119 are positivelyheld out of its path of travel. Only after the machine has completed acycle (that is, only after machine element 102a has been stroked) doessafety mechanism 100 operate safety block 119 to the safety position.Only after safety block 119 is at its safety position does handrestraint safety mechanism 100a operate to the released position therebyextending cables 116 and 118 to provide the operator with manual accessto the machine work area for unloading the completed workpiece andloading a new workpiece. It will thus be observed that the operator canhave manual access to the machine work area only when safety block 119is at its safety position. Moreover, since the hand restraints are notreleased until safety block 119 is at its safety position, it will alsobe noted that manual access to the machine work area cannot occur untilmovement of all elements on the machine, including safety block 119, hasceased.

Details of safety mechanism 100 are shown in FIGS. 3-12. Attention isfirst directed to FIGS. 3-5 showing the sturdily constructed rectangularhousing 100a having a vertical back wall 100b, top and bottom walls1006, 100d and side walls 100e, 100f. The open interior of housing 1000is enclosed by a removable cover which has been removed from FIG. 3 toexpose the interior construction. Cable guides 120, 122 for guidingcables 116, 118 into and out of housing 100a are mounted at the lowercorners of housing 100a. A pneumatic cylinder 57, hereinafter referredto as restraint cylinder 57, is centrally mounted on top wall I000 abovehousing 100a. A suitable circular opening 100g is provided in top wall100C through which the rod 57a of restraint cylinder 57 extends into theinterior of housing 100a. Rod 57a also passes through a valve body 160on the inside of Wall 1000, and details of body 160 will be explainedlater. As best seen in the solid line position of FIG. 3 (which, as willbecome apparent, represents the released position of the handrestraints), a bushing 124 is affixed to the free end of rod 57a, and acable attaching member 126 in the form of a generally square plate isaffixed to bushing 124. A roller 128 is mounted on member 126 and ridesin a guideway 130, formed between a pair of guide members 132 and 134 onback wall 100b. A valve member 162 in the form of a generally roundplate is mounted on bushing 124 and yieldably coupled with member 126.As will be explained later, valve member 162 is cooperatively associatedwith valve body 160, this arrangement constituting one of the severalembodiments of failsafe valves disclosed herein. As best seen in FIG. 6,valve member 162 is journaled on bushing 124 by a large circular bore162a to permit member 162 to slide lengthwise thereon. Four smallerthreaded bores 16212 are arranged 90 apart around bore 162a, and each iscounterbored at 162C to receive one end of a coil spring 164. The otherend of each coil spring 164 lodges in a corresponding counterbore 126!)(FIG. 3) of a corresponding bore 126a in member 126. The threaded shanksof headed guide pins 166 are passed through bores 126a to engage bores162b and thereby compress springs 164 such that member 162 is yieldablymounted for lengthwise displacement on bushing 124 relative to member126. A pair of circular pads 162p, 162r (FIG. 6) are affixed to theupper surface of member 162 on opposite sides of bore 162a; as will beseen later, pads 162p, I62r close respective bores in valve body 160when the safety mechanism is in the restraining position. Note also thatthe side of member 162 facing wall 100a has a flat l62f.

A pair of cable guiding sleeves 136, 138 extend from. cable guides 120,122, respectively, to a mounting bracket 140 which is affixed to wall100b in alignment with, but somewhat spaced from cable attaching member126. Cables 116, 118, upon entering housing 100a via guides 120, 122,are guided through sleeves 136, 138, respectively, and the ends of thecables are affixed der 57. Valve 54 has a plunger 54p positioned foractu- Thus, after pads 162p, l62r abut body 160 to arrest further travelof member 162 relative thereto, cylinder rod 57a continues along a finalincrement of travel toward the retracted position while member 162 isincreasingly displaced on bushing 124 toward member 126 against thespring force of springs 164 with member 126 continuing to move withcylinder rod 57a over the final increment of travel toward the retractedposition. When cylinder rod 57a is extended from the retracted position,member 162 initially remains in abutment with valve body 160 untilmember 126 has been extended to abut the heads of guide pins 166 afterwhich member 162 also beings to move with cylinder rod 57a away fromvalve body 160.

A plurality of four valves, 54, 65, 70 and 78 are mounted on wall 100bfor actuation in accordance with the position to which member 126 isoperated by cylination by the head of a stud 126d threaded into a tappedhole in the bottom surface of member 126; valve 54 being disposed foroperation to its actuated, or tripped,

, position when cylinder rod 57a is fully extended (i.e.,

to member 126. Helical springs 142, 144 are disposed 100a, therebyretracting hand restraints 112, 114, and.

hence the operators hands, to the restraining position. During operationof cylinder 57, roller 128 guides member 126 along guideway 130. It willbe observed that with the safety mechanism 100a in the restrainingposition, valve member 162 has been displaced on bushing 124 towardmember 126 because of abutment with valve body 160 via the plastic pads162p, 162r. Valve member 162 and valve body 160 are arranged in relationto the stroke of cylinder rod 57a such that pads 162p, 162r abut thelower surface of body 160 prior to cylinder rod 57a arriving at theretracted position.

hand restraints in the released position) and stud 126d provides aconvenient adjustment for attaining this result. Valves 65, and 78 arestocked (FIG. 4) and have their roller-type plungers 65p, 70p and 78ppositioned for actuation by member 126. A cam surface 1266 is fashionedalong a portion of the upper side edge of member 126 so that plunger 70pis actuated slightly before plungers 65p and 78p as member 126approaches the restraining position. Thus valves 65, 70 and 78 areactuated when cylinder rod 57a is fully retracted (i.e., hand restraintsin the restraining position), but with valve 70 being actuated slightlybefore valves 65 and 78 as the cylinder rod retracts. A valve 83 (shownonly in FIG. 11) is positioned adjacent valve 54 for actuation by member126 when the latter is in the released (i.e., illustrated) position. Apalm-button operated reset valve 51 is mounted on housing 100a betweencable guides 120, 122. Details of the pneumatic circuit arrangement ofthe above valves will be covered in the description of FIG. 11.

A low air pressure safety interlock 149 (see FIG. 3) mechanicallyrestricts the travel of cylinder rod 57a when the system supply line airpressure drops below a predetermined level. By way of example, this mayoccur when anominal pressure of psi drops below 60-65 psi. A rectangularblock 150 is affixed to wall b alongside the top end of guide 134. Aguideway a is fashioned in block 150 at a right angle to the travel ofcylinder rod 57a. A second guideway l50b is fashioned in block 150 tointercept guideway 150a at a right angle. A slide 152 is guided inguideway 150a and is shiftable lengthwise of the guideway into and outof the path of travel of member 126 by means of a pneumatic cylinder 52.Cylinder 52 has a cylinder rod 52a connected to a piston 52b and thelater is engaged by a coil spring 52c such that: rod 52a, and henceslide 152, are urged to the extended position. (The drawing, however,illustrates cylinder 52 and slide 152 in the retracted position.) In theretracted position, slide 152 clears the path of travel of member 126,thereby permitting the latter to freely move between the released andrestraining positions when cylinder 57 is operated. However, whencylinder rod 52a is fully extended, slide 152 is disposed within thepath of travel of member 126, thereby restricting the travel of thelatter. Thus, if

7 member 126 is in the restraining (broken line) position (of FIG. 3)when cylinder 52 moves slide 152 into the path of travel of member 126,then it is impossible for cylinder rod 57a to be fully extending andthus hand restraints 112, 114 cannot be moved to the released position.If member 126 is in the released position when slide 152 is shifted intothe path of travel of member 126, then member 126 cannot be brought tothe restraining position, and as will be seen later, machine element102a cannot be .stroked. Note that will slide 152a extended, member 162does not hit the slide because of the clearance provided by flat l62f.Another cylinder 68 is mounted on block 150 in alignment with guideway150b. A slide 169 is affixed to the cylinder rod 68a of cylinder 68, andis guided in guideway 150b. A coil spring 680 biases the piston 68!) ofcylinder 68 to urge cylinder rod 68a, and hence slide 169, toward theretracted position. (The drawing, however, illustrates cylinder 68 andslide 169 in the latched position.) With cylinder rod 68a in theretracted position, the end of slide 169 clears guideway 150a. However,when sufficient air pressure is introduced into the head end of cylinder68, the bias of spring 680 is sufficiently overcome to move slide 169into guideway 150a. With cylinder rod 52a retracted, slide 169 latchesin a groove 152a fashioned in the side of slide 152. As long assufficient air pressure continues to be supplied to cylinder 68, thelatching engagement of slide 169 with groove 152a is maintained to holdslide 152 clear of the path of travel of member 128. However, when thesupply line pressure drops below a predetermined level, the

, force of spring 680 is sufficient to remove slide 169 from groove 152aand when this happens, spring 520 urges slide 152 into the path oftravel of member 126. This condition remains until the system is resetand sufficient air supply pressure again exists, This aspect along withthe way in which cylinders 52 and 68 are connected in the pneumaticcontrol circuit will be explained in greater detail in connection withthe description of FIG. 11. A pilot supply valve 53 is mounted on block150 and has its plunger 53p actuated by a pin 152b on slide 152 when thelatter is out of the path of travel of member 126. The connection ofvalve 53 in circuit will also be covered in the description of FIG.

In accordance with important features of the present arrangement, afailsafe circuit is provided whereby it is impossible for machine 102 tobe stroked when the hand restraints are in other than the restrainingposition, and the safety block in other than the retracted position;This failsafe circuit is embodied in part by the construction details ofvalve body 160. Therefore, attention is directed to FIGS. 7-10 whichillustrate these details. Body 160 is of generally square shape andmounted on the inside of top wall 1000 in general alignment withcylinder 57. Valve body 160 comprises a large cylinder hole 161 alignedwith hole 100g in the housing top wall (FIG. 3). Rod 57a passes throughhole of cylinder 57 whereby both cylinder 57 and body 160 l are mountedto wall 1000 A pair of shallow bores 166,

, 168 are fashioned in the surface of member 160 which faces member 162,and are on diametrically opposite sides of hole 161. A pair of small,thin passages 166a,

166b extend upwardly through member 160 from the interior end of bore166. A pair of holes 1660 and 166d for reception of pneumatic linefittings are fashioned in one side of body 160 at right angles topassages 166a, 1661). A small, thin passage 166:: extends into body 160from the interior end of hole 1660 to intercept the interior end ofpassage 166a. A small, thin passage 166fextends from the interior end ofhole 166d to intercept the interior end of passage 166b. In similarfashion, a

' pair of small, thinpassages 168a and 168 b extend into block 160 fromthe interior end of bore 168. These two passages are intercepted bypassages 1680 and 168d, which latter passages extend from the interiorends of holes 168:; and 168fformed in the side of member 160 oppositeholes 1660 and 166d. In order to effect connection of pneumatic linefittings at the side of member 160 which faces wall f, a pair of holes168g and l68h are fashioned therein and'small, thin passages 168i and168j extendfrom the interior ends of these latter two holes to interceptpassages 1680 and 168d. Holes 168e and 168]" are plugged by plugs 168e'and 168]. As mentioned earlier, valve member 162 is cooperativelyassociated with valve body 160. When valve member 162 abuts valve body160, pads 162p, 162r close on bores 166 and 168 respectively. With bore166 closed by pad 162p, a pneumatic fluid path, through which a fluidicsignal can pass, is created between hole 1660 and hole 166d via passages166e, 166a, bore 166, and passages 166b and I66f; and with bore 168closed by pad l62r, a pneumatic fluid path, through which a fluidicsignal can pass, is createdbetween hole 168g and hole l68h via passages168i, 1680, 168 a, bore 168, and passages 168b, 168d and 168]. Thusthese constructions provide a pair of failsafe valves availableforconnection in pneumatic circuit. As will be seen in FIG. 11', only oneof these valves is utilized and is identified by the numeral 66 in thatfigure. The fluid path through each valve such as 66 is createdimmediately upon abutment of valve member 162 with body since member 162is yieldable mounted on member 126, valve 66 can conduct a fluidicsignal as member 126 moves over its final increment of travel to therestraining position.

As will be seen later, other failsafe valves (such as valve 83 mentionedearlier) are used in the present invention. All such failsafe valves arefunctionally identical to failsafe valve 66; that is, only when anactuating member closes the open bore of the failsafe valve (such asmember 162 closing on bore 166 in valve 66) is a fluid path createdthrough which a fluidic signalcan be transmitted.

Body 160 is also constructed to provide a three-way, exhaust valve whichis identified by the numeral 72 in FlG. 11. As will be laterseen in FIG.11, valve 72 forms a portion of an emergency release circuit. A bore 170extends vertically through body 160 at one side thereof and the upperend thereof is doubly counterbored as at 170a and 170b.A valving member172 is slidable arranged within bore 170 and comprises a circular head172a which fits snugly within counterbore 170b. One endof a spring 176is contained within the bore'l72b of member 172 and the other end ofthe-spring bears shoulder between counterbores 170a and 170b and thefashioned in the side of member 160 facing wall lime and small, thinpassages 178a, 1800, respectively, extend from the interior ends thereofto intercept counterbore 170a. An exhaust passage 182 (FIGS. 7 and 8) isfashioned in member 160 to intercept counterbore 17011. In theillustrated position a pneumatic fluid path exists between holes 178 and180. As will be seen in greater detail herein, in connection with thedescrip-.

tion of FIG. 11, when valve member 172 is displaced upwardly (i.e., tothe left in FIGS. 8 and 10), the path between holes 178 and 180 isinterrupted by being vented to exhaust via passage 182.

The schematic diagram of the pneumatic control circuit of safetymechanism 100 is shown in FIGS. 11 and 12. FIG. 11 schematicallyillustrates the arrangement of the pneumatic circuit components whichare contained within housing 100a while FIG. 12 illustrates theremaining components, which'are exterior of hous' ing 100a. Sincevarious pneumatic circuit components within housing 100a must beoperatively coupled with various components exterior of housing 100a,certain pneumatic lines must be routed both interior of and exterior ofhousing 100a. Such routing'is effected via a junction J (FIG. 11) whichmates with a mating junction J (FIG. 12). The connection of similarlynumbered pneumatic lines in FIGS. 11 and 12 are via similarly numberedconnections at each junction. For example, connection 3 of junction Jmates with connection 3 of junction J to couple the portion of line 203in FIG. 11 with the portion of line 203 in FIG. 12.

The portion of the circuit in FIG. 11 comprises the following circuitcomponents: reset valve 51 (mentioned earlier in FIGS. 3 and 5), whichis a twoposition, three-way, spring-returned, palm-operated, normallyclosed type; the low air pressure safety interlock 149 describedearlier) which is composed of cylinder 52, pilot supply valve 53, whichis a two-position, three-way, spring-returned, mechanically-actuatedtype, and cylinder 68; control valve 54 (mentioned earlier in FIG. 3),which is a two-position, three-way, spring-returned,mechanically-actuated type; a supply valve 55, which is a two-position,threeway, springreturned, air-actuated type; a master valve 56, which isa two-position, four-way, five-ported, air-returned, air-' actuatedtype; a pilot valve 58 which is a two-position, four-way, five-ported,air-returned, air-actuated type; a

shuttle valve 62, which is a shuttle type; cam valve 65 (mentionedearlier in FIGS. 3 and 4), which is atwoposition, three-way,spring-returned, cam-actuated type; failsafe valve 66 (mentioned earlierin FIGS.

' 7-10); cam valve '70 (mentioned earlier in FIGS. 3 and 4) which is atwo-position, three-way, springreturned, cam-actuated, normally opentype; exhaust valve 72 (described earlier in FIGS. 7-10); a pilot valve78 (mentioned earlier in FIGS. 3 and 4) which is a twoposition,three-way, cam'actuated, air-returned type; a pilot valve 80, which is atwo-position, three-way, mechanically-actuated, spring-returned type; apilot valve 82, which is a two-position, three-way,mechanically-actuated, springreturned-type; a failsafe valve 83, whichis functionally equivalent to failsafe valve 66; a failsafe valve 84,which is functionally equivalent to failsafe valve 66; a failsafe valve85, which is functionally equivalent to failsafe valve 66; and a pilotcylinder 81 which, as will be explained in greater detail hereinafter,is operatively associated with valves 78, 80, 82, 84, and in thepneumatic circuit to constitute a nonrepeat circuit 250. While valves55, 56, 58,80, 82, 83,

' 84, 85 and cylinder 81 are contained in housing a,

they, along with the various pneumatic lines interconnecting the valveshave been omitted for sake of clarity in FIG. 3 and related mechanicaldrawing figures.

In FIG. 12 the remainder of the circuit is seen to comprise the follwingcomponents: foot pedal valve 60 (mentioned earlier in FIG. 1), which isa two-position, four-way, spring-returned, foot-actuated type; a camvalve 67, which is a two-position, three-way, spring returned,cam-actuated, normally closed type; a cam valve 69, which is atwo-position, three-way, springreturned, cam-actuated, normally closedtype; an emergency valve 71 which is a two-position, three-way,spring-returned, palm-actuated, normally closed type; a master valve 73,which is a two-position, four-way, air-actuated, airreturned, type; afailsafe valve 74, which is functionally equivalent to failsafe valve66; a pilot valve 75, which is a two-position, three-way, airactuated,spring-returned type; a failsafe valve 76, which is functionallyequivalent to. failsafe valve 66; a pilot valve 77, which is atwo-position, three-way, mechanically-actuated, spring-returned type; apilot valve 79, which is a two-position, three-way, mechani-Cally-actuated, spring-returned type; a failsafe valve 86, which isfunctionally equivalent to failsafe valve 66; and cylinder 63 (mentionedearlier in FIG. 1) for operating safety block 119.

In the ensuing description, all valves are selectively operable betweenan actuated position and 21 released (or returned) position. Formechanically-actuated, cam-actuated or air-actuated, spring-returnedvalves, the actuated position thereof refers to that position where thevalve actuator is displaced against the bias of its spring, and thereleased position refers to the valve position to which the valveactuator is normally biased by the spring. All air actuated orcam-actuated, airreturn valves are illustrated in the returned position.For failsafe valves 66, 74, 76., 83, 84, 85 and 86, the actuatedposition refers to that position of the valve wherein the valve canconduct a fluidic signal. For valve 72, the actuated position refers tothe position where it vents to exhaust. FIGS. 11 and 12 illustrate thesafety mechanism in the following condition: cylinder 57a fully extended(i.e., hand restraints released); foot pedal valve 60 released; cylinder63 fully extended (i.e., safety block 119 in the safety position); andthe low air pressure safety interlock 149 reset. Machine element 102a isstopped at its upper limit of travel.

Looking now at the detailed circuit arrangement of the above components,valves 67, 69 and 86 (FIG. 12) are arranged for actuation inpredetermined relation to the stroke of machine element 102a. Valves 67and 86 are pneumatically coupled in series by a pneumatic line 216a totransmit a fluidic signal only when machine element 102a is at its upperlimit of travel (i.e., at top dead center or ram-up position); valve 69is arranged to transmit a fluidic signal only when element 102a is atits lower limit of travel (i.e., bottom dead center). More specifically,the system air supply line L connects to inlet 67a of valve 67 and toinlet 69a of valve 69. Outlet 67b of valve 67 connects'via line 216a toport 86c of valve 86, and .port 86b of valve 86 connects via line 216 tothe inlet 58a of valve 58in FIG. 11'. Port 670 of valve 67 vents toexhaust. Outlet 69b of valve 69 connects via line 210 to the airactuating pilot 58p of valve 58. Proper valve actuation is attained byan operative coupling with machine 102. This operative cou pling may bewith any element (or elements) of machine 102 so long as valves 67 and86 are operated to their actuated positions when machine element 102a isat top dead center and valve 69 is operated to its actuated positionsome time during the stroke of element 102a (for example, when element102a is at bottom dead center). One possible way of actuating valves 67and 69 is via a rotary cam 190 which rotates in synchronism with thestroke of machine element 102a, making one revolution for each stroke(one revolution constituting a downstroke and an upstroke). When machineelement 102a comes to bottom dead center, valve 69 is actuated by cam190 to transmit air to pilot 58p. Only when machine element 102a is attop dead center or rest is valve 67 actuated (as illustrated in thedrawing) by cam 190 to transmit air to port 86c of failsafe valve 86.The open bore 86a of valve 86 is closed by another cam actuator (notshown in FIG. 12) as element 102a completes a final increment of itsupstroke. (The particular construction details of valve 86 will beexplained later in FIGS. 13 and 14.) Hence, as element 102a completesits upstroke, valve 86 is actuated just prior to valve 67 so that air istransmitted through the two valves to inlet 58a of valve 58 only afterelement 102a has arrived at top dead center. It is desirable andbeneficial to actuate valve 86 slightly before valve 67 so that the camactuator for valve 86 does not have to close against the force of a jetof air being exhausted through bore 86a which would be the case if valve67 were actuated first. Thus, valves 67 and 86 constitute a failsafecircuit for sensing when element 102a is at top dead center.

Valves 73, 74, 76, 77 and 79 (FIG. 12) are operatively associated withthe mechanical safety interlock provided by block 119 and cylinder 63.Valve 73 is arranged to control the extension and retraction of cylinderrod 63a to which block 119 is affixed. The system air supply line Lconnects to the inlet 73a of valve 73 while the outlet 73b of the valveconnects via line 225 to the head end of cylinder 63. The rod end ofcylinder 63 connects via line 226 to port 730 of the valve and port 73dvents to exhaust. The return pilot 73r of valve 73 connects via line 211with port 580 of valve 58 in FIG. 11. The actuating pilot 73p of valve73 connects via line 208 with port 166d of failsafe valve 66 in FIG. I].With valve 73 in the return position as illustrated in the drawing,valve 73 supplies air to the head end of cylinder 63 and vents the rodend thereof, whereby cylinder rod 63a is extended to move safety block119 to the safety position. When valve 73 is in the actuated position,it supplies air to the rod end of cylinder 63 and vents the head endthereof, whereby cylinder rod 63a is retracted to return safety block119 to the retracted position. Valves 76 and 77 are connected in seriesand constitute a failsafe circuit for sensing when safety block 119 isin the safety position. In similar fashion, valves 74 and 79 areconnected in series and constitute a failsafe circuit for sensing whensafety block 119 is in the retracted position. More specifically, line211 connects to inlet 77a of valve 77; outlet 77b of valve 77 connectsvia line 227 to port 76b of valve 76; port 76c of valve 76 connects vialine 211a 79 by operating the actuator to inlet 62a of shuttle valve 62in FIG. 11. When safety block 119 is in the safety position asillustrated in the drawing, an actuating arrangment which is movablewith cylinder rod 63, and is only schematically illustrated in FIG. 12,actuates valve 76 by closing the open bore 76a thereof and actuatesvalve 77 via the actuator 77p thereof. Desirably, valve 76 is arrangedfor actuation just prior to actuation of valve 77 as safety block 119approaches the safety position. Thus, when safety block 119 is at thesafety position, air can be conducted through valves 77 and 76 to inlet62a of shuttle valve 62. In similar fashion, when safety block 119 isretracted, the actuating arrangment on cylinder rod 63a now actuatesvalve 74 by closing the bore 74a thereof and valve 74 79p thereof.Preferably valve 74 is actuated just prior to valve 79. Thus, withsafety block 119 in the retracted position, air can be conducted fromport 166d of valve 66 in FIG. 11 through valves 74 and 79 to pilot p ofvalve 75. Supply line L connects to inlet 75a of valve 75 and outlet 75bto machine 102. Thus, when valve 75 is actuated, a signal is transmittedtherethrough to machine 102, and this signal is used to initiate astroke of element 1020.

Still considering FIG. 12, line 203 connects inlet 60a of valve 60 withport 830 of valve 83 in FIG. 11; ports 60b and 600 of valve 60 connectvia lines 204 and 2040, respectively, with non-repeat circuit 250 inFIG. 11; port 60d vents to exhaust. In the illustrated released positionof valve 60, it can transmit air from port 830 of valve 83 to port 810of cylinder 81 while venting the other port 81d of cylinder 81 toexhaust. When valve 60 is actuated, it can transmit air from port 830 toport 81d while venting port 81a c to exhaust. Valve 71 is utilized inthe emergency release circuit mentioned before and its circuitconnection and operation will be explained later when the emergencyrelease circuit is described.

Turning now to details of FIG. 11 and first to nonrepeat circuit 250,cylinder 81 comprises a piston 81pv which, when equal pressures exist atports 81c and 81d, is biased to the center of the cylinder by a pair ofsprings 81r and 81s which bear against opposite sides of piston 81pwithin the cylinder. When pressure is supplied to port 81c and not toport 81d as illustrated in the drawing, piston 81p is displaced upwardlyagainst the bias of spring 81s. An actuator 81a at the upper end of thecylinder is movable with piston 81p and is arranged to actuate valves 82and 85 when piston 81p is displaced upwardly within the cylinder. Whenpressure is supplied to port 81 d and not to port 810, piston 81p isdisplaced downwardly against the bias of spring 81r. In this position anactuator 81b at the lower end of the cylinder actuates valves 80 and 84.

Valves 82 and are connected in series and constitute a failsafe circuitfor sensing when piston 81p is displaced upwardly within cylinder 81.More specifically, the inlet 82a of valve 82 connects via line 203 toport 830 of valve 83; outlet 82b of valve 82 connects to port 850 ofvalve 85; port 85b of valve 85 connects via line 229 to the return pilot781' of valve 78; and port 820 of valve 82 vents to exhaust. With piston81p displaced upwardly within cylinder 81 (as illustrated) actuatingarrangement 81a closes the bore 85a of valve 85 and actuates valve 82via the actuator 82p thereof. Desirably, valve 85 is actuated justbefore valve 82 as piston 81p is displaced upwardly. Thus, with piston81p displaced fully upwardly within cylinder 81, valves 82 and whenpiston 8p is displaced downwardly within cylinder I 81. In particular,outlet 78b of valve 78 connects via line 228 to inlet 80a of valve 80;outlet 80b of valve 80 connects via line 228a to port 84c of valve 84;port 84b of valve 84 connects via line 204a to the air-actuating pilot56p of valve 56; and port 80c of valve 80 vents to exhaust. Inlet 78a ofvalve 78 connects via line 203 with port 830 of valve 83 and the port780 of valve 78 vents to exhaust. When piston 81p is displaceddownwardly within cylinder 81, actuating arrangment 81b closes the bore84a of valve 84 and actuates valve 80 via the actuator 80p thereof.Desirably, valve 84 is actuated just before valve 80 as piston 81p isdisplaced downwardly. Thus, with valve 78 in its return position, asillustrated, valves 80 and 84 can transmit air from valve 83 to pilot56p when piston 81p is displaced fully downwardly within cylinder 81. Aswill be explained more detailedly hereinafter, non-repeat circuit 250prevents the safety mechanism and the machine from executing more than asingle cycle at a time by requiring foot pedal valve 60 to be releasedand then actuated before a subsequent cycle can occur.

Considering still further details of FIG. 11, reset valve 51 is providedto reset the safety mechanism at the beginning of the operating sequenceif resetting is required. The system air supply line L is connected tothe inlet 51a of valve 51 and outlet 51b of valve 51 is coupled via apneumatic line 201 with the rod end of cylinder 52. With thisarrangement, when valve 51 is operated to the actuated positon (asillustrated), it opens to supply air to cylinder 52 thereby displacingcylinder rod 520 (FIG. 3) to the retracted position and hence movingslide 152 out of the path of travel of member 126. Supply line L is alsodirectly connected to the head end of cylinder 68. So long as sufficientline air pressure is available, cylinder 68 is extended to latch slide169 in groove 152a to lock cylinder rod 52a in the retracted position,and hold slide 152 out of the path of travel of member 126. Thiscondition is maintained after valve 51 is released to its returnposition only so long as sufficient line pressure exists. When the linepressure drops below a predetermined minimum, slide 169 unlatches slide152 thereby permitting the latter to be disposed in the path of travelof member 126. Hence, a safety is provided in the event of loss ofsystem pressure.

Supply line L also connects to inlet 53a of valve 53 and the outlet 53bof valve 53 connects via line 202 to pilot 55p of valve 55. Outlet 530of valve 53 vents to exhaust. As will be remembered from earlierdescription, since valve 53 is actuated when low air pressure safetycircuit 149 is reset, valve 53 supplies air to inlet 54a and pilot 55pso long as the line air pressure remains above the predeterminedminimum. Line L also connects to inlet 55a of valve 55, and with pilot55p being actuated, valve 55 transmits air to valve 56 via line 221which connects between outlet 55b of valve 55 and inlet 56a of valve 56.Thus, so long as the system air pressure is above the predeterminedminimum, air is always supplied to inlet 56a. Outlet 56b of valve 56connects via line 205 to the rod end of cylinder 57 and the head end ofcylinder 57 connects via line 212 with port 56c of valve 56. Ports 56aand 56:: of valve 56 vent to exhaust. With this arrangement, when valve56, is in the return position as illustrated in the drawing, ittransmits air to the head end of cylinder 57 and vents the rod endthereof to exhaust whereby cylinder rod 57a is extended. When valve 56is' int'he actuated position, it transmits air to the rod end ofcylinder 57 and vents the head end thereof to exhaust, whereby cylinder57a is retracted. As will be seen later, valve 56 is operated to theactuated position in response to air supplied via line 204a fromnon-repeat circuit 250 and to the return position via air supplied topilot 56r through shuttle valve 62 from the safety block circuit.

Line 202 also connects to inlet 54a of valve 54. The outlet 54b of valve54 connects to port 83b of valve 83, while port 54c of valve 54 vents toexhaust. Valves 54 and 83 are connected in series and constitute afailsafe circuit for sensing when cylinder rod 57a is fully extended andhence, sensing when the hand restraints are in the released position.Thus, when valve 54 is actuated by actuator 126 and the bore 83a ofvalve 83 is closed by pad 83p, air is transmitted through the two valvesto those circuit components which are commonly connected via line 203 toport 83c Preferably, valve 83 is actuated just before valve 54 ascylinder rod 57aapproaches the extended position.

In addition to the connections to valve 58 which have already beenenumerated, outlet 58b of valve 58 con- .nects via line 206 to inlet 65aof valve 65. Ports 58d and 58e vent to exhaust. Outlet 65b of valve 65connects via line 207 to port 1666 of valve 66. Thus, valves 65 and 66are connected in series and constitute a failsafe circuit for sensingwhen cylinder rod 57a is fully retracted and hence, sensing when thehand restraints are in the restraining position. Because of theyieldable connection of member 162 on member 126, bore 166 is closed bypad 162p just prior to the actuation of valve 65 by member"'l26.' Thus,when the hand restraints are fully retracted, a signal from valve 58 canbe transmitted through valves 65 and 66 to valve 73. Valve 78 is alsoactuated by member 126 when cylinder rod 57a is fully retracted.

In light of the foregoing detailed description of the various portionsof FIGS. 11 and 12, the overall operation of the safety mechanism cannow be fully appreciated. First, if necessary, valve 51 is actuated toreset circuit 149. Safety block 119 is in the safety position and thehand restraint safety mechanism 100a is in the released position. Afteroperator 106 has loaded a workpiece into machine 102, he actuates valve60. This causes piston 81p to be displaced downwardly within cylinder81, thereby actuating valves and 84. Since valves 54 and 83 arepresently all actuated, the actuation of valves 80 and 84 causes air tobe supplied to pilot 56p of valve 56, thereby operating this lattervalve to the actuated position. Cylinder 57 now begins to retract,thereby operating hand restraint safety mechanism 100a to therestraining; position.

As cable attaching member 126 retracts, it releases valves 54 and 83.Accordingly, port 81d of cylinder 81 vents to exhaust and springs 81sand 81 r center piston 81p within cylinder 81 whereby all four valves80, 82,

84 and 85 are now released. Note also that pilot 56p now vents toexhaust.

When member 126 is fully retracted, valves 65 and .66 are actuated tocause the air which is presently being transmitted through valve 67,valve 86 and valve 58 to the inlet 65a of valve 65 to be furthertransmitted through valves 65 and 66 to pilot 73p of valve 73. Sincepilot 73r is presently being vented through valve 58, valve 73 operatesto the actuated position to thereby retract safety block 119 from thesafety position to the retracted position. From this operatingarrangement, it will be observed that the hand restraint must be in theretracted position before safety block 119 can be retracted from itssafety position and failsafe operation isattained via the failsafecircuit of valves 65 and 68. As block 119 begins to retract from thesafety position,

valves 76 and 77 are released. Release of these valves vents inlet 62aof valve 62 to exhaust so that it now becomes impossible for valve 56 toextend cylinder rod 57a. Hence, so long as safety block 119 is away fromits safety position, the operator is prevented by the hand restraintmechanism from having manual access to the work area of the machine.When safety block 119 is fully retracted, valves 74 and 79 are actuated.The air signal from valve 66 is now transmitted through valve 79 andvalve 74 to actuate valve 75 and supply a signalto machine 102 forinitiating the stroke of element 1020. Note that because of the failsafecircuit constituted by valves 74 and 79 which is in series with thefailsafe circuit constituted by valves 65 and 66, both the handrestraints and the safety block must be. in the retracted positionsbefore machine element 102a can stroke. Thus, optimum safety is ensured.

As machine element 102a begins its downstroke, valve 67 is released andthis removes air from all circuits which are supplied from it, ventingthese to exhaust. However, nothing else happens immediately. When valve69 is actuated, pilot 58p is energized,

thereby actuating valve 58, pilot 58r having been previously vented toexhaust. Valve 67 is again actuated at shuttle valve 62 and hence tooperate valve 56 to the return position since, as mentioned before,pilot 56p is presently vented to exhaust. Now, cylinder rod 570 extendsto release the hand restraints. It will be noted that such extension canoccur only when the failsafe circuit constituted by valves 76 and 77senses that safety block 119 is in the safety position. Thus, only afterall moving I elements on the machine have stopped, including safetyblock 119, is it possible for the hand restraints to release.

When the member 126 is fully extended, valves 54 and 83 are actuated tosupply air to all components which connect commonly with line 203.Hence, valve 58 operates to the return position and air is supplied toinlet 60a, inlet 78a and inlet 82a. Shifting of valve 58 to the returnposition permits air from valve 67 to be supplied to inlet 65a of valve65 but since 65 is closed,

the air is transmitted no further.

Since valve 78 was closed by member 126 when the hand restraints wereretracted, it will be observed that air to valves 80 and 84 is blocked.Accordingly, if the t operator is still actuating foot pedal valve 60 atthe conclusion of the cycle of the safety mechanism, piston 81p cannotbe displaced downwardly within cylinder 81 to actuate valves 80 and 84.Hence, cylinder rod 57a is prevented from retracting. The non-repeatcircuit thereby prevents a subsequent cycling from occurring. The onlyway for a subsequent cycle to occur is if the operator releases valveafter valves 54 and 56 have been actuated. When this is done, piston 81pis displaced upwardly within cylinder 81 to actuate both valves 82 and85. The air being supplied from valve 83 to valve 82 is now transmittedthrough valves 82 and 85 to pilot 78r of valve 78, thereby shifting thislatter valve to the return position. In the return position, valve 78opens to supply air to inlet 80a of valve 80. However, since piston 81pis now at its upper position, valves 80 and 84 are released and thesignal to valve 56 for extending cylinder rod 57a can be transmittedthrough valves 80' and 84, only be actuating valve 60 to move piston 81pdownwardly within cylinder 81. Thus, the non-repeat feature providesparticularly advantageous operation in preventing a subsequent cycleshould the foot pedal 60 be depressed at the conclusion of an operatingcycle. However, it will be noted that even if a subsequent cycle were toaccidentally occur for any reason whatsoever, the hand restraint safetywould still fouled or snagged thereby preventing safety mechanism frombeing operated to the restraining position. Withvalves 72 and 70 intheir non-actuated positions, valve 71,.when actuated, conducts air fromline L via line 218 through valve 70 and then via line 219 through valve72 and then via line 220 to inlete62b of shuttle I valve 62. In turn,valve 56 is operated by pilot 56r to its return position. Sinceactuation of valve 71 will customarily occur only when cylinder rod 57ais being retracted, valve 56 is always shiftable to the return positionbecause pilot 56jpvents toexhaust upon release of foot pedal valve 60.With valve 56 thus shifted to the returnposition, the travel of cylinderrod 57a is immediately reversed to operate the safety mechanism to thereleased position. The fouled cable(s) may then be cleared. u

Valve 72 also provides a failsafe feature which disables the emergencyrelease circuit when the safety mechanism is in the restrainingposition. Because the connection between lines 219 and 220 is brokenwhen valve member 72 is displaced by valve member 162, valve 56 cannotbe shifted to the return position with the safety mechanism in therestraining position. Since valve 70 is actuated just prior to actuationof valve 65, the emergency release circuit is disabled just prior to thetransmission of the signal from valve 66 to valve 73.

Thus it is impossible for the hand restraints ,to be released by theemergency release circuit after movement of safety block 119 hascommenced.

Having described the overall operation of the safety mechanism,attention is now directed to the remaining drawing figures whichillustrate specific details of failsafe valves which maybeadvantageously used in the system. FIGS. 13 and 14 illustrate specificdetails of valve 86'which is utilized in FIG. 12. Ports 86b and 86c arein the form of nipple fittings threaded into respective bores in,thebody of the valve. These valve body bores open into the common bore 860which is open at the lower concavely curved surface of the valve body.When bore 860 is closed by a closure element such as element 86d (shownin FIG. 13 only), a fluid circuit path is completed between ports 86band 86c. As mentioned earlier in FIG. 12, valve 86 is arranged foractuation in timed relation with the stroke of machine element 102a andas particularly illustrated-by way of example in FIG. 12, via a camoperatively coupled with cam 190. Thus, in FIG. 13, element 86dconstitutes a cam arranged for rotation with cam 190 to selectivelyclose bore 860a; more specifically, element 86d is arranged for rotary,tangential movement, relative to the lower curved surface of the valvebody as indicated by the arrow in FIG. 13. Excellent closure of member86d with the valve body around bore 86a is attained via the mountingstructure 260 for mounting valve 86. Mounting structure 260 comprises abase 262 which is disposed adjacent the rotary path of element 86d.Valve 86 is affixed by a pair of bolts 266 to one end of an armstructure 268 whose opposite end is hinged on base 262 as at 270. Arm268 is biased in the clockwise direction about hinge 270 to thereby biasvalve 86 generally radially inwardly ot' the axis about which element86d rotates. This biasing arrangement is provided by a stud 271 whichextends upwardly from base 262 passing through a hole 272 in arm 268. Anut 274 is threaded onto the upper end of stud 271 and a helical spring276 is compressed between nut 274 and arm 268 to thereby urge armagainst a shoulder 271a on stud 271. The compression force in spring 276may be varied by ad justing nut 274 on stud 271, and the radial positionto which valve 86 is biased relative to element 86d may be adjusted byvertically adjusting stud 271 on base 262. A nut 276' locks stud 271 onbase 262. Withthis arrangement, valve 68 is normally biased to aposition wherein the radially inner (or lower as viewed in the againstthe force of spring 276. When element 86d stops at the solid lineposition of FIG. 13, it closes valve bore 86a and spring 276 exertsaclosure force between the two whereby effective sealing and tightclosure are attained. When element 86d begins to rotate at the beginningof the next operating stroke of machine 102, it releases the valve,thereby opening bore 86a.

FIG. 15 and 16 disclose a further embodiment of failsafe valveidentified by the numeral 280. Valve 280 comprises a two-piece bodyformed by solid rectangular body elements 282 and 284 fastened togetherby a pair of bolts 286. A central circular bore 288 extends through bodyelement 282 and aligns with a bore 290 in body element 284, the upperend of which is counterbored as at 292. A valving member 294 comprisinga cylindrical stem 296 and an enlarged cylindrical head 298 has the stem296 passing through bore 288, counterbore 292 and bore 290. An annularretaining element 298 is affixed to stem 296 within counterbore 292. Ahelical compression spring 300 is affixed to stem 296 within counterbore292 around stem 296. The lower end of spring 300 bears against theshoulder between bore 290 and counterbore 292 and the upper end ofspring 300 bears against retaining ring 298 to urge the ring against thelower surface of body element 282 around bore 288. Hence, spring 300biases valving member 294 upwardly relative to the valve body so thathead 298 is normally spaced from the top surface of body element 282.Head 298 is a solid but has an annular groove 302 fashioned in theunderside thereof around stem 296. An annular groove 304 is fashioned inthe top surface of body element 282 around and slightly outwardly frombore 288. A pair of passages 306a, 306b extend downwardly from thebottom of groove 304 at one side of bore 288 to intercept a perpendicular bore 308 extending into the body element 282 from the frontsurface thereof. Another pair of bores 310a and 31% extend downwardlyfrom the bottom of groove 304 at the opposite side of bore to intercepta perpendicular bore 312 extending into body element 282 from the frontsurface thereof. In the illustrated position of FIG. 15, a pneumaticsignalentering one of the bores 308, 312 simply vents to exhaust;however, when valving member 294 is displaced downwardly to seat head298 against the top surface of the valve body, groove 302 in cooperationwith groove 304 provides communication between the.two bores,308

314 is that in valve 314, abody element 316 replaces body element 282.Body element 316 comprises a deeper annular groove 304 which intersectsa pair of parallel bores 318, 320 extending into body element 316 fromopposite sides thereof on diametrically oppoi site sides of bore 288.When valving member294 is displaced downwardlyto close "head 298 on thetop surface of body member 316, a llluidic signal may be conductedbetween bores 318 and 320 via grooves 304 and 302. Thus, it will beperceived valve 314 operates in the same fashion as valve 280 to attainthe desired failsafe operation.

F IGS, 19, 20 and 21 disclose different forms of actuators for failsafevalves. Turning first to FIG. 19, the ac tuator 322 shown thereincomprises a tubular body 324 within which a cylindrical actuatingelement 326 is arranged for axial displacement. A tubular bushing 328 ispressed into the upper end of the bore of body 324 and a helical spring330 is disposed around element 326 between the lower end of bushing 328and a slioulder 332 of element 326. With this arrangement, element 326is biased downwardly relative to body 324 with downward movement ofelement 326 limited by a retaining ring 334 on the upper end thereof Iwhich bears against the upper end of bushing 328. The lower, or head,end of element 326 comprises a circular plastic sealing disk 336inserted into a circular recess in the lower surface of member 326 andis adapted to seal against the open bore of a failsafe body such as thebore 166 in FIGS. 7-l0. Actuator 322 is particularly useful in that itdoes not require the more complicated biasing arrangement such as thatof valve 66 since the yieldable mounting is internally contained. Thus,in usage, body 324 may be affixed to the movable mechanism element whoseposition the failsafe valve is to sense; the actuator element 326 can bedisplaced to accommodate the final increment of travel of the movingmechanism element.

FIG. 20 illustrates an actuator 338 in the form of a stud which may bethreaded into a hole in the movable mechanism element whose position thefailsafe valve is to sense. Actuator 338 has a plastic sealing disk 340in the head end thereof. The threaded mounting of actuator 338 permitsadjustment thereof relative to the failsafe valve body.

FIG. 21 illustrates a further form of actuator 342 having a circularsealing disk 344 at the lower end thereof. The upper end thereof has athreaded bore 346 via which the actuator may be mounted to the movablemechanism element whose position the failsafe valve is to sense. Thethreaded bore 346 permits convenient adjustment of the actuator relativeto the failsafe valve body.

It is to be understood that the foregoing description is that of apreferred embodiment of the invention. Various changes and modificationsmay be made without departing from the spirit and scope of the inventionas defined by the appended claims.

I claim:

1. Safety mechanism for use by an operator of a machine having at leastone machine elment which moves during each machine operating cycle: saidsafety mechanism including hand restraint apparatus comprising handrestraint means for the hands of the operator and hand restraint movingmeans operatively coupled with said hand restraint means for controllingthe movement of said hand restraint means between a released positionwhich permits at least one of the operators hands to be disposed in thepath of travel of said at least one machine element and a restrainingposition which prevents both of the operators hands from being disposedin the path of travel of said at least one machine element; a mechanicalsafety interlock means controllably operable to a safety positionwherein the same is disposed in the path of travel of said at least onemachine element for bodily stopping travel thereof and to a retractedposition wherein said mechanical safety interlock means clears the pathof travel of said at least one machine element; a mechanical safetyinterlock moving means for moving said mechanical safety interlock meansbetween said two operative positions thereof; and control means forinterlocking said hand restraint moving means, said mechanical safetyinterlock moving means and the machine such that a machine operatingcycle can begin only when both said hand restraint means is in itsrestraining position and said mechanical safety interlock means is inits retracted position.

2. The safety mechanism of claim 1 wherein said control means comprisesmeans for causing said mechanical safety interlock means to remain inits safety position so long as said hand restraint means is in itsreleased position.

3. The safety mechanism of claim 1 wherein said control means comprisesmeans for causing said mechanical safety interlock means to remain inits safety position so long as said hand restraint means is in otherthan its restraining position.

4. The safety mechanism of claim 1 wherein said control means comprisesmeans for preventing said mechanical safety interlock means fromoperating from its safety position to its retracted position unless saidhand restraint means is in its retraining position.

5. The safety mechanism of claim 1 wherein said control means comprisesmeans responsive to the conclu sion of each machine operating cycle forcausing said mechanical safety interlock means to operate from itsretracted position to its safety position and means for causing saidhand restraint means to operate from its restraining position to itsreleased position only after said mechanical safety interlock means isin its safety position.

6. The safety mechanism of claim 5 wherein said control means comprisesmeans for preventing said mechanical safety interlock means fromoperating from its safety position to its retracted position unless saidhand restraint means is in its restraining position.

7. The safety mechanism of claim 1 wherein said control means includesactuator means actuable by the machine operator for initiating anoperating cycle of the safety mechanism and the machine.

8. The safety mechanism of claim 7 wherein said control means includesmeans responsive to actuation of said actuator means for executing anoperating cycle of the safety mechanism and the machine wherein: saidhand restraint means operates from its released position to itsrestraining position whereby the operators hands are removed from thepath of travel of said at least one machine element; then, saidmechanical safety interlock means operates from its safety position toits retracted position; then, the machine executes its operating cycle;then, said mechanical safety interlock means operates from its retractedposition to its safely position; and then, said hand restraint meansoperates from its restraining position to its released position wherebythe operator can once again have manual access to the machine.

9. The safety mechanism of claim 8 wherein said control means includesfailsafe sensing circuit means for sensing when said hand restraintmeans is in its restraining position, said failsafe sensing circuitmeans comprising means forming a fluid circuit path through which afluidic signal may be conducted to indicate that said hand restraintmeans is in its restraining position.

10. The safety mechanism of claim 8 wherein said control means includesfailsafe sensing circuit means for sensing when said hand restraintmeans is in its released position, said failsafe sensing circuit meanscomprising means forming a fluid circuit path through which a fluidicsignal may be conducted to indicate that said hand restraint means is inits released position.

11. The safety mechanism of claim 8 wherein said control means includesfailsafe sensing circuit means for sensing when said mechanical safetyinterlock means is in its safety position, said failsafe sensing circuitmeans comprising means forming a fluid circuit path through which afluidic signal may be conducted to indicate that said mechanical safetyinterlock means is in its safety position.

12. The safety mechanism of claim 8 wherein said control means includesfailsafe sensing circuit means for sensing when said mechanical safetyinterlock means is in its retracted position, said failsafe sensingcircuit means comprising means forming a fluid circuit path throughwhich a fluidic signal may be conducted to indicate that said mechanicalsafety interlock means is in its retracted position.

13. The safety mechanism of claim 8 wherein said control means furthercomprises non-repeat circuit means responsive to actuation of saidactuator means for preventing a subsequent operating cycle of the safetymechanism and the machine unless said actuator means is released afteractuation thereof.

14. The safety mechanism of claim 13 wherein said non-repeat circuitmeans comprises: selectively operable means selectively operable to afirst state wherein an operative connection exists between said actuatormeans and said handrestraint moving means through which operation ofsaid hand restraint moving means can be initiated by actuation of saidactuator means and to a second state wherein saidoperative connection isbroken; means for causing said selectively operable means to switch fromits first stateto its second state after operation of said handrestraint moving means has been initiated in response to actuation ofsaid actuator means; and means for causing said selectively operablemeans to return to its first state in response to release ofsaidactuator means. v

15. The safety mechanism of claim 14 wherein said control meanscomprises means for causing said selectively operable means to switchfrom its first state to its second state only after said hand restraintmeans begins to travel from its released position to its restrainingposition.

16. The safety mechanism of claim 15 wherein said control meanscomprises means for permitting said selectively operable means to switchfrom its second state back to its first state only after the conclusionof an operating cycle.

'17. The safety mechanism of claim 1 wherein said mechanical safetyinterlock moving means comprises a mechanical safety interlock means isat said one operative position thereof.

23. The safety mechanism of claim 22 wherein said two valves arearranged such that said closure means completes the fluid path betweensaid two bores of said failsafe valve means before said three-way valveopens.

24. The safety mechanism of claim 20 wherein said failsafe sensingcircuit means is arranged to sense the safety position of saidmechanical safety interlock means.

25. The safety mechanism of claim 24 wherein said control means includesmeans operatively coupling said failsafe sensing circuit means with saidhand restraint moving means such that when said failsafe sensing circuitmeans completes said fluid path, a signal is transmitted therethrough tocause said hand restraint moving means to operate from its restrainingposition to its released position.

26. The safety mechanism of claim 20 wherein said failsafe sensingcircuit means. is arranged to sense the retracted position of saidmechanical safety interlock means.

27. The safety mechanism of claim 26 wherein said control means includesmeans operatively coupling power cylinder having an extendable andretractable rod.

18. The safety mechanism of claim 17 wherein said mechanical safetyinterlock means comprises a metal block affixed to the rod of said powercylinder.

19. The safety mechanism of claim 1 wherein said control means includesfailsafe sensing circuit means operatively associated with saidmechanical safety in terlock means for sensing when said mechanicalsafety interlock means is at one of its two operative positions.

20. The safety mechanism of claim 19 wherein said failsafe sensingcircuit means comprises a pair of sensing elements connected in seriescircuit and forming a fluid path through which a fluidic signal may beconducted when said mechanical safety interlockmeans is in said oneoperative position thereof.

21. The safety mechanism of claim 20 wherein one of said sensingelements comprises a failsafe valve means, said failsafe valve meanscomprising closure means movable with said mechanical safety interlockmeans, a valve body disposed in the path of travel of said closuremeans, a pair of bores in said body open toward said closure means, saidclosure means and said valve body being arranged and constructed suchthat when said mechanical safety interlock means is in said oneposition, said closure means abuts said valve body to complete a-fluidpath between said two bores, said two bores being operatively coupled influid circuit with said control means to conduct a fluid signalindicative of the mechanical safety interlock means being at said oneoperative positionthereof.

22. The safety mechanism of claim 21 wherein the other sensing elementcomprises a normally closed three-way valve connected in series withsaid failsafe valve means, said threeway valve opening when said saidfailsafe sensing circuit means with the machine such that when saidfailsafe sensing circuit means completes said fluid path, a cycle startsignal is supplied to the machine for initiating the operating cyclethereof. 28. A hand restraint safety apparatus for use by an operator ofa machine having at least one machine element which moves during eachmachine operating cycle, said apparatus comprising: hand restraint meansfor the handsof the operator and hand restraint moving means operativelycoupled with said hand restraint means for controlling the movement ofsaid hand restraint means between a released position which permits atleast one of the operators hands to be disposed in the path of travel ofsaid at least one machine element and a restraining position whichprevents both of the operators hands from being disposed in the path oftravel of said at least one machine element; control circuit meansoperatively coupling said hand restraint moving means and the machine;said control circuit means comprising an actuator means selectivelyoperative to actuated and released positions; said control circuit meansfurther comprising coupling circuit means operatively coupling saidactuator means with said hand restraint moving means and the machinesuch that upon operation of said actuator means to the actuatedposition, said hand restraint moving means and the machine execute anoperating cycle wherein said hand restraint means is first operated tothe restraining position by said hand restraint moving means, themachine is then cycled and said hand restraint means is then operated tothe released position by said hand restraint moving means; said couplingcircuit means including non-repeat circuit means responsive to theoperation of said actuator means to the actuated position for preventinga subsequent operating cycle unless said actuator means is returned tothe released position.

I 29 The hand restraint safety apparatus of claim 28 wherein saidcoupling circuit means includes means for operatively disconnecting saidhand restraint moving means from said actuator means after said handrestraint moving means has been actuated in response to an initialactuation of said actuator means and means responsive to return of saidactuator means to the released position to again operatively couple saidactua tor means to said hand restraint moving means so that a subsequentcycle may be commenced by again actuating said actuator means.

30. The hand restraint safety apparatus of claim 29 wherein saidcoupling circuit means further includes means for preventing said handrestraint moving means from being operatively recoupled to said actuatormeans unless said hand restraint means is in the released position.

31. The hand restraint safety apparatus of claim 28 wherein saidnon-repeat circuit means comprises switchable means switchable betweenfirst, and second conditions, said switchable meanswhen in said firstcondition operatively coupling said actuator means with said handrestraint moving means such that said hand restraint moving means isresponsive to actuation of said actuation means and said switchablemeans when in said second condition operatively disconnects said handrestraint moving from said actuator ,means such that saidhand restraintmoving means is nonresponsive to actuation of said actuator means, saidswitchable, means being switched from its first condi tion to its secondcondition after said actuator means has initiated operation of said handrestraint moving means.

38. The hand restraint safety apparatus of claim 37 wherein said valvemeans includes an additional valve means connected in series circuitwith said failsafe valve means, said additional valve means beingarranged to provide an open path therethrough prior to the beginning ofan operating cycle so that the fluid signal can be transmitted throughsaid fluid circuit tosaid hand restraint moving means to initiate acycle, said ad- 32. The hand restraint safety apparatus of claim 31wherein said switchable means can be switched from its second conditionback to its first condition only with said actuator means in thereleased position. j

33; The handrestraint safety apparatus of claim 28 signalhis transmittedto said hand restraint moving wherein said coupling circuit meansincludes: means forming afluidic circuit path through which a fluidic,

means'to initiate operation thereof when said actuator.

means is actuated; means for closing path after a fluidic signal hasbeen transmitted 'therethrough to initiate an v operating cycle; andmeans for again opening said path only after said actuator means hasbeen returned to its released position. i i

34. The hand restraintjsafety apparatus wherein said coupling circuitmeans includes valve means responsive tothe operation of said handrestraint moving means such that said fluid circuit path after oncebeing closed can again open only when said hand restraint moving meansisin the releasedposition.

35. The hand restraint safetyapparatus of claim 34 wherein said couplingcircuit means includes a failsafe valve means for opening and closingsaid fluid path.

36. The hand restraintsafety apparatus of claim 28 wherein saidnon-repeat circuit means comprises a of claim 33 straint moving means toinitiate an operating cycle, and

means responsive to the initiation of such a cycle for operating saidfluid actuated device to its second posi-- tion whereby the fluid signalto said hand restraint moving means is then terminated.

37. The hand restraint safety apparatus of claim 36 wherein said valvemeans includes a failsafe valve means.

tion.

valve means being open only when said hand restraint means is inreleasedposition. r t

40. The hand restraint safety appara tus of claim 28 wherein saidcoupling circuit means includes; means forming a fluidie 'circuit paththrough which a fluidic signalcan betransrnitted to said hand restraintmoving means to initiate operation thereof whensaid actuator means isactuated, said fluidic circuit path including a first valve -meansand asecond valve means; a fluid actuateddevice operatively coupled with'saidactuator means and'said first and second valve means for operating saidfirst and secondvalve means such that prior to the beginning of anoperating cycle, said first valve means is closed andsaid second valvemeans isopen, said, first valve means is openedby said device inresponse to operation of said actuator means from thereleased positionto the actuated position whereby a fluidic signal can be transmittedthrough said fluid circuit path to said hand restraint moving meanstoinitiate op.- eration there of, and said second valve means is closedbysaid device after an operating cycle has been initiated and remainsclosed so long as said actuator me ans remains infthe actuated position.i

41; The hand restraint safety apparatus of claim 40 wherein said'fluidactuated device is operatively coupled with said, actuatormeans and saidsecond valve means such that said second a valve means can be opened bysaid device at the end of an operating cycle by operating said actuatormeans to the released posi- 42. The hand: restraint safety apparatus of'claim 40 wherein said coupling circuit means includesmeans. forming asecond fluidic circuit path through which a fluidic signal can be.transmitted to said second valve means to operate the same to. the openposition thereof, saidsecond fluidic circuit path including a thirdvalvemeans therein for opening and closing said. second fluidic circuitpath,said third valve means being positioned to be actuated by said devicesuch that when said acttiator means operates to the released positionsaid device operates to open said third valve means thereby supplyingthe fluidic signal for opening 'said 45. The hanad restraint safetyapparatus of claim 40 wherein said fluid actuated device comprises afluid cylinder having movable means thereon movable to a first positionto actuate said first valve means and to a second position to actuatesaid second valve means, said fluid cylinder being operatively coupledwith said actuator means and said first and second valve means such thatwhen said actuator means operates from the released position to theactuated position said fluid cylinder operates to the first positionthereby actuating said first valve means and when said actuator meansoperates from the actuated position to the released position, said fluidcylinder operates to its second position thereby actuating said secondvalve means.

46. The hand restraint safety apparatus of claim 45 wherein said fluidcylinder, said actuator means, and said first valve means are alsoarranged such that said first valve means can be operated from itsclosed position to its open position only when said hand restraint meansis in the released position.

47. The hand restraint safety apparatus of claim 45 wherein said fluidcylinder, said actuator means, and said second valve means are alsoarranged such that said second valve means can be operated from itsclosed position to its open position only when said hand restraint meansis in the released position.

48. The hand restraint safety apparatus of claim 45 wherein said fluidcylinder is operative to a third position wherein neither said firstvalve means not second valve means is actuated, said fluid cylinderbeing operated to the third position after said hand restraint movingmeans has begun to operate in response to receipt of the fluidic signalthrough said first and second valve means.

49. The hand restraint safety apparatus of claim 48 wherein said fluidcylinder can operate from the third position to the second position onlywhen said actuator means is in the released position.

50. The hand restraint safety apparatus of claim 49 wherein said fluidcylinder can operate from the third position to the second position onlywhen said hand restraint means is also in its released position.

51. The hand restraint safety apparatus of claim 48 wherein said fluidcylinder comprises biasing means for biasing said movable means of saidcylinder in said third position, said movable means being movable fromthe third position to the first position in one direction and from thethird position to the second position in the other direction.

52. A hand restraining safety apparatus for use by an operator of amachine having operating mechanism including at least one machineelement movable between a retracted position and an operative position,said apparatus comprising hand restraining means for a hand 'of themachine operator positionable in a first position in which the operatorshand may be positioned contig-' uous to said machine element and asafety position in which the operators hand is restrained at a spacedposition from the one machine element, and operating means for movingsaid hand restraining means from its first position to its safetyposition when said machine element is in itsretracted position, andsafety means positionable in the path of travel of a portion of saidmachine operating mechanism for bodily preventing the one machineelement from moving from its retracted position to its operativeposition so long as said hand restraining means is in other than itssafety position. 1

.53. A hand restraining safety apparatus of claim 52 wherein said safetymeans is positionable in the path of travel of said one machine element.

1. Safety mechanism for use by an operator of a machine having at leastone machine elment which moves during each machine operating cycle: saidsafety mechanism including hand restraint apparatus comprising handrestraint means for the hands of the operator and hand restraint movingmeans operatively coupled with said hand restraint means for controllingthe movement of said hand restraint means between a released positionwhich permits at least one of the operator''s hands to be disposed inthe path of travel of said at least one machine element and arestraining position which prevents both of the operator''s hands frombeing disposed in the path of travel of said at least one machineelement; a mechanical safety interlock means controllably operable to asafety position wherein the same is disposed in the path of travel ofsaid at least one machine element for bodily stopping travel thereof andto a retracted position wherein said mechanical safety interlock meansclears the path of travel of said at least one machine element; amechanical safety interlock moving means for moving said mechanicalsafety interlock means between said two operative positions thereof; andcontrol means for interlocking said hand restraint moving means, saidmechanical safety interlock moving means and the machine such that amachine operating cycle can begin only when both said hand restraintmeans is in its restraining position and said mechanical safetyinterlock means is in its retracted position.
 2. The safety mechanism ofclaim 1 wherein said control means comprises means for causing saidmechanical safety interlock means to remain in its safety position solong as said hand restraint means is in its released position.
 3. Thesafety mechanism of claim 1 wherein said control means comprises meansfor causing said mechanical safety interlock means to remain in itssafety position so long as said hand restraint means is in other thanits restraining position.
 4. The safety mechanism of claim 1 whereinsaid control means comprises means for preventing said mechanical safetyinterlock means from operating from its safety position to its retractedposition unless said hand restraint means is in its retraining position.5. The safety mechanism of claim 1 wherein said control meaNs comprisesmeans responsive to the conclusion of each machine operating cycle forcausing said mechanical safety interlock means to operate from itsretracted position to its safety position and means for causing saidhand restraint means to operate from its restraining position to itsreleased position only after said mechanical safety interlock means isin its safety position.
 6. The safety mechanism of claim 5 wherein saidcontrol means comprises means for preventing said mechanical safetyinterlock means from operating from its safety position to its retractedposition unless said hand restraint means is in its restrainingposition.
 7. The safety mechanism of claim 1 wherein said control meansincludes actuator means actuable by the machine operator for initiatingan operating cycle of the safety mechanism and the machine.
 8. Thesafety mechanism of claim 7 wherein said control means includes meansresponsive to actuation of said actuator means for executing anoperating cycle of the safety mechanism and the machine wherein: saidhand restraint means operates from its released position to itsrestraining position whereby the operator''s hands are removed from thepath of travel of said at least one machine element; then, saidmechanical safety interlock means operates from its safety position toits retracted position; then, the machine executes its operating cycle;then, said mechanical safety interlock means operates from its retractedposition to its safely position; and then, said hand restraint meansoperates from its restraining position to its released position wherebythe operator can once again have manual access to the machine.
 9. Thesafety mechanism of claim 8 wherein said control means includes failsafesensing circuit means for sensing when said hand restraint means is inits restraining position, said failsafe sensing circuit means comprisingmeans forming a fluid circuit path through which a fluidic signal may beconducted to indicate that said hand restraint means is in itsrestraining position.
 10. The safety mechanism of claim 8 wherein saidcontrol means includes failsafe sensing circuit means for sensing whensaid hand restraint means is in its released position, said failsafesensing circuit means comprising means forming a fluid circuit paththrough which a fluidic signal may be conducted to indicate that saidhand restraint means is in its released position.
 11. The safetymechanism of claim 8 wherein said control means includes failsafesensing circuit means for sensing when said mechanical safety interlockmeans is in its safety position, said failsafe sensing circuit meanscomprising means forming a fluid circuit path through which a fluidicsignal may be conducted to indicate that said mechanical safetyinterlock means is in its safety position.
 12. The safety mechanism ofclaim 8 wherein said control means includes failsafe sensing circuitmeans for sensing when said mechanical safety interlock means is in itsretracted position, said failsafe sensing circuit means comprising meansforming a fluid circuit path through which a fluidic signal may beconducted to indicate that said mechanical safety interlock means is inits retracted position.
 13. The safety mechanism of claim 8 wherein saidcontrol means further comprises non-repeat circuit means responsive toactuation of said actuator means for preventing a subsequent operatingcycle of the safety mechanism and the machine unless said actuator meansis released after actuation thereof.
 14. The safety mechanism of claim13 wherein said non-repeat circuit means comprises: selectively operablemeans selectively operable to a first state wherein an operativeconnection exists between said actuator means and said hand restraintmoving means through which operation of said hand restraint moving meanscan be initiated by actuation of said actuator means and to a secondstate wherein said operative connection is broken; means for causingsaid selectively operable means to switCh from its first state to itssecond state after operation of said hand restraint moving means hasbeen initiated in response to actuation of said actuator means; andmeans for causing said selectively operable means to return to its firststate in response to release of said actuator means.
 15. The safetymechanism of claim 14 wherein said control means comprises means forcausing said selectively operable means to switch from its first stateto its second state only after said hand restraint means begins totravel from its released position to its restraining position.
 16. Thesafety mechanism of claim 15 wherein said control means comprises meansfor permitting said selectively operable means to switch from its secondstate back to its first state only after the conclusion of an operatingcycle.
 17. The safety mechanism of claim 1 wherein said mechanicalsafety interlock moving means comprises a power cylinder having anextendable and retractable rod.
 18. The safety mechanism of claim 17wherein said mechanical safety interlock means comprises a metal blockaffixed to the rod of said power cylinder.
 19. The safety mechanism ofclaim 1 wherein said control means includes failsafe sensing circuitmeans operatively associated with said mechanical safety interlock meansfor sensing when said mechanical safety interlock means is at one of itstwo operative positions.
 20. The safety mechanism of claim 19 whereinsaid failsafe sensing circuit means comprises a pair of sensing elementsconnected in series circuit and forming a fluid path through which afluidic signal may be conducted when said mechanical safety interlockmeans is in said one operative position thereof.
 21. The safetymechanism of claim 20 wherein one of said sensing elements comprises afailsafe valve means, said failsafe valve means comprising closure meansmovable with said mechanical safety interlock means, a valve bodydisposed in the path of travel of said closure means, a pair of bores insaid body open toward said closure means, said closure means and saidvalve body being arranged and constructed such that when said mechanicalsafety interlock means is in said one position, said closure means abutssaid valve body to complete a fluid path between said two bores, saidtwo bores being operatively coupled in fluid circuit with said controlmeans to conduct a fluid signal indicative of the mechanical safetyinterlock means being at said one operative position thereof.
 22. Thesafety mechanism of claim 21 wherein the other sensing element comprisesa normally closed three-way valve connected in series with said failsafevalve means, said three-way valve opening when said mechanical safetyinterlock means is at said one operative position thereof.
 23. Thesafety mechanism of claim 22 wherein said two valves are arranged suchthat said closure means completes the fluid path between said two boresof said failsafe valve means before said three-way valve opens.
 24. Thesafety mechanism of claim 20 wherein said failsafe sensing circuit meansis arranged to sense the safety position of said mechanical safetyinterlock means.
 25. The safety mechanism of claim 24 wherein saidcontrol means includes means operatively coupling said failsafe sensingcircuit means with said hand restraint moving means such that when saidfailsafe sensing circuit means completes said fluid path, a signal istransmitted therethrough to cause said hand restraint moving means tooperate from its restraining position to its released position.
 26. Thesafety mechanism of claim 20 wherein said failsafe sensing circuit meansis arranged to sense the retracted position of said mechanical safetyinterlock means.
 27. The safety mechanism of claim 26 wherein saidcontrol means includes means operatively coupling said failsafe sensingcircuit means with the machine such that when said failsafe sensingcircuit means completes said fluid path, a cycle start signal issupplied to the machine for initiating the opeRating cycle thereof. 28.A hand restraint safety apparatus for use by an operator of a machinehaving at least one machine element which moves during each machineoperating cycle, said apparatus comprising: hand restraint means for thehands of the operator and hand restraint moving means operativelycoupled with said hand restraint means for controlling the movement ofsaid hand restraint means between a released position which permits atleast one of the operator''s hands to be disposed in the path of travelof said at least one machine element and a restraining position whichprevents both of the operator''s hands from being disposed in the pathof travel of said at least one machine element; control circuit meansoperatively coupling said hand restraint moving means and the machine;said control circuit means comprising an actuator means selectivelyoperative to actuated and released positions; said control circuit meansfurther comprising coupling circuit means operatively coupling saidactuator means with said hand restraint moving means and the machinesuch that upon operation of said actuator means to the actuatedposition, said hand restraint moving means and the machine execute anoperating cycle wherein said hand restraint means is first operated tothe restraining position by said hand restraint moving means, themachine is then cycled and said hand restraint means is then operated tothe released position by said hand restraint moving means; said couplingcircuit means including non-repeat circuit means responsive to theoperation of said actuator means to the actuated position for preventinga subsequent operating cycle unless said actuator means is returned tothe released position.
 29. The hand restraint safety apparatus of claim28 wherein said coupling circuit means includes means for operativelydisconnecting said hand restraint moving means from said actuator meansafter said hand restraint moving means has been actuated in response toan initial actuation of said actuator means and means responsive toreturn of said actuator means to the released position to againoperatively couple said actuator means to said hand restraint movingmeans so that a subsequent cycle may be commenced by again actuatingsaid actuator means.
 30. The hand restraint safety apparatus of claim 29wherein said coupling circuit means further includes means forpreventing said hand restraint moving means from being operativelyrecoupled to said actuator means unless said hand restraint means is inthe released position.
 31. The hand restraint safety apparatus of claim28 wherein said non-repeat circuit means comprises switchable meansswitchable between first and second conditions, said switchable meanswhen in said first condition operatively coupling said actuator meanswith said hand restraint moving means such that said hand restraintmoving means is responsive to actuation of said actuation means and saidswitchable means when in said second condition operatively disconnectssaid hand restraint moving from said actuator means such that said handrestraint moving means is non-responsive to actuation of said actuatormeans, said switchable means being switched from its first condition toits second condition after said actuator means has initiated operationof said hand restraint moving means.
 32. The hand restraint safetyapparatus of claim 31 wherein said switchable means can be switched fromits second condition back to its first condition only with said actuatormeans in the released position.
 33. The hand restraint safety apparatusof claim 28 wherein said coupling circuit means includes: means forminga fluidic circuit path through which a fluidic signal is transmitted tosaid hand restraint moving means to initiate operation thereof when saidactuator means is actuated; means for closing path after a fluidicsignal has been transmitted therethrough to initiate an operating cycle;and means for again opening said path only after said actuator means hasBeen returned to its released position.
 34. The hand restraint safetyapparatus of claim 33 wherein said coupling circuit means includes valvemeans responsive to the operation of said hand restraint moving meanssuch that said fluid circuit path after once being closed can again openonly when said hand restraint moving means is in the released position.35. The hand restraint safety apparatus of claim 34 wherein saidcoupling circuit means includes a failsafe valve means for opening andclosing said fluid path.
 36. The hand restraint safety apparatus ofclaim 28 wherein said non-repeat circuit means comprises a fluidactuated device operable to first and second positions, meansoperatively coupling said actuator means with said device such that thelatter operates to the first position thereof in response to operationof said actuator means from its released position to its actuatedposition, a fluid circuit comprising a valve means responsive to theoperation of said fluid actuated device to its first position forsupplying a fluid signal to said hand restraint moving means to initiatean operating cycle, and means responsive to the initiation of such acycle for operating said fluid actuated device to its second positionwhereby the fluid signal to said hand restraint moving means is thenterminated.
 37. The hand restraint safety apparatus of claim 36 whereinsaid valve means includes a failsafe valve means.
 38. The hand restraintsafety apparatus of claim 37 wherein said valve means includes anadditional valve means connected in series circuit with said failsafevalve means, said additional valve means being arranged to provide anopen path therethrough prior to the beginning of an operating cycle sothat the fluid signal can be transmitted through said fluid circuit tosaid hand restraint moving means to initiate a cycle, said additionalvalve means being arranged to close in response to operation of saidhand restraint moving means, said additional valve means being openedagain only in response to return of said actuator means to the releasedposition.
 39. The hand restraint safety apparatus of claim 38 whereinsaid fluid circuit includes a still further valve means connected inseries with said additional valve means and said failsafe valve means,said still further valve means being open only when said hand restraintmeans is in released position.
 40. The hand restraint safety apparatusof claim 28 wherein said coupling circuit means includes: means forminga fluidic circuit path through which a fluidic signal can be transmittedto said hand restraint moving means to initiate operation thereof whensaid actuator means is actuated, said fluidic circuit path including afirst valve means and a second valve means; a fluid actuated deviceoperatively coupled with said actuator means and said first and secondvalve means for operating said first and second valve means such thatprior to the beginning of an operating cycle, said first valve means isclosed and said second valve means is open, said first valve means isopened by said device in response to operation of said actuator meansfrom the released position to the actuated position whereby a fluidicsignal can be transmitted through said fluid circuit path to said handrestraint moving means to initiate operation thereof, and said secondvalve means is closed by said device after an operating cycle has beeninitiated and remains closed so long as said actuator means remains inthe actuated position.
 41. The hand restraint safety apparatus of claim40 wherein said fluid actuated device is operatively coupled with saidactuator means and said second valve means such that said second valvemeans can be opened by said device at the end of an operating cycle byoperating said actuator means to the released position.
 42. The handrestraint safety apparatus of claim 40 wherein said coupling circuitmeans includes means forming a second fluidic circuit path through whicha fluidic signal can be Transmitted to said second valve means tooperate the same to the open position thereof, said second fluidiccircuit path including a third valve means therein for opening andclosing said second fluidic circuit path, said third valve means beingpositioned to be actuated by said device such that when said actuatormeans operates to the released position said device operates to opensaid third valve means thereby supplying the fluidic signal for openingsaid second valve means.
 43. The hand restraint safety apparatus ofclaim 42 wherein said third valve means includes a failsafe valve means.44. The hand restraint safety apparatus of claim 40 wherein said firstvalve means includes a failsafe valve means.
 45. The hanad restraintsafety apparatus of claim 40 wherein said fluid actuated devicecomprises a fluid cylinder having movable means thereon movable to afirst position to actuate said first valve means and to a secondposition to actuate said second valve means, said fluid cylinder beingoperatively coupled with said actuator means and said first and secondvalve means such that when said actuator means operates from thereleased position to the actuated position said fluid cylinder operatesto the first position thereby actuating said first valve means and whensaid actuator means operates from the actuated position to the releasedposition, said fluid cylinder operates to its second position therebyactuating said second valve means.
 46. The hand restraint safetyapparatus of claim 45 wherein said fluid cylinder, said actuator means,and said first valve means are also arranged such that said first valvemeans can be operated from its closed position to its open position onlywhen said hand restraint means is in the released position.
 47. The handrestraint safety apparatus of claim 45 wherein said fluid cylinder, saidactuator means, and said second valve means are also arranged such thatsaid second valve means can be operated from its closed position to itsopen position only when said hand restraint means is in the releasedposition.
 48. The hand restraint safety apparatus of claim 45 whereinsaid fluid cylinder is operative to a third position wherein neithersaid first valve means nor second valve means is actuated, said fluidcylinder being operated to the third position after said hand restraintmoving means has begun to operate in response to receipt of the fluidicsignal through said first and second valve means.
 49. The hand restraintsafety apparatus of claim 48 wherein said fluid cylinder can operatefrom the third position to the second position only when said actuatormeans is in the released position.
 50. The hand restraint safetyapparatus of claim 49 wherein said fluid cylinder can operate from thethird position to the second position only when said hand restraintmeans is also in its released position.
 51. The hand restraint safetyapparatus of claim 48 wherein said fluid cylinder comprises biasingmeans for biasing said movable means of said cylinder in said thirdposition, said movable means being movable from the third position tothe first position in one direction and from the third position to thesecond position in the other direction.
 52. A hand restraining safetyapparatus for use by an operator of a machine having operating mechanismincluding at least one machine element movable between a retractedposition and an operative position, said apparatus comprising handrestraining means for a hand of the machine operator positionable in afirst position in which the operator''s hand may be positionedcontiguous to said machine element and a safety position in which theoperator''s hand is restrained at a spaced position from the one machineelement, and operating means for moving said hand restraining means fromits first position to its safety position when said machine element isin its retracted position, and safety means positionable in the path oftravel of a portion of said machine operating mechanism for bodilypreventing the one machine element from moving from its retractedposition to its operative position so long as said hand restrainingmeans is in other than its safety position.
 53. A hand restrainingsafety apparatus of claim 52 wherein said safety means is positionablein the path of travel of said one machine element.